Refractory-material grate



April 13 1926. 1.5s0,21s

O. O. NYGAARD REFRACTORY MATERIAL GRATE Filed July 29, 1920 2 Sheets-Sheet l April 13 1926.

O. O. NYGAARD REFRACTORY MATERIAL GRA'IE 2 Sheets-Sheet 2 Filed July 29, 1920 I 72226 77x60 7 M Q 7 M K ai-Jfy I 1,580,215 PATENT OFFICE.

OSCAR O. NYGAARD, OF SAUGUS, MASSACHUSETTS.

REFRACTORY-MATERIAL GRATE.

Application filed July 29, 1920. Serial No. asasos.

To all whom it may concern:

Be it known that I, OSCAR O. NYGAARD, a citizen of the United States, and resident of Saugus, in the county of Middlesex and State of Massachusetts, have invented an Improvement in Refractory-Material Grates, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My present invention is a fire grate brick, block, box or tuyere, intended and designed to take the place of iron grates, tuyeres, and the like, particularly in the modern forms of automatic stokers.

'Heretofore it has been customary to employ fire brick of common form and vanous sizes, for the walls of furnaces, but I believe it to be a distinct novelty to devise and provide a grate block, t-uyere or the like of any form, made of refractory material such for example, carborundum and preferably molded, dried and burned in substantially the same manner as the manufacture of fire brick, which refractory material shall be practically equivalent to and a substitute for the iron grates, tuyeres and the like. I find that it is feasible and practical to form the usual fire clay or similar refractory. material into suitable shapes to take the place of the usual grate bars or tuyere plates and to burn these refractory tuyeres or fire brick or plate articles, in a kiln, so that their surfaces will be vitrified and suflicientlyhardened to withstand the frictional abrasion of fuel, such as burning coal, and also to so form my refractory fire brick with a plurality of air openings therethrough, that air under forced draft can be supplied through such refractory material in a manner substantially identical with that now employed in iron grates and tuyere plates. The present excessive cost of iron, delays in securing. it, difficulties in transportation and the like, have created considerable difliculties in the building and repairingof modern automaticstokers. My

invention, therefore, is of great importance in enabling uch automatic stokers to be equipped with refractory tuyere lates, made at a locality adjacent the stoker at very slight expense. Furthermore, such refractory tuyere blocks can be quickly, easily and readily removed and renewed, without trouble, when damaged or broken, and, of course, can be demolished for quick and casy removal if desired, whereas an iron tuyere block, when warped, twisted or melted down, is frequently very diflicult to extract from the stoker. These advantages are of special importance at the present time and are of value in the further development and use of automatic stokers. It is well known in underfeed stoker practice that the height of the usual iron tnyeres covering the air channels between retorts is very limited. The maximum height measured at right angles to the edges on which the tuyeres rest is considered to be five inches from the lowermost tuyere opening to the uppermost opening.

This limitation is understood from the fact that the temperature in the middle and upper zones of the fuel bed in an underfeed stoker furnace is usually over 3000 degrees F. and the'melting point of cast,iron about 2200 degrees.

Although the air circulating through the tuyere helps keep it cool, it has been found insufficient to preserve the iron should the tuyere be extended higher into the fire bed,

consequently the upper surface of an iron tuyere must be kept close enough to the retort to have the additional protection of the I comparatively fresh fuel being fed from the retort.

' No such limitation is necessary in my refractory tuyere where the melting point is 4000 degrees F. and therefore capable of withstanding the temperature in the fuel bed even without the'protection of the air circulation,-and with such circulation mak ing my refractory tuyere absolutely immune to the temperature in the fuel bed.

a From this it will be understood that it is practical with my refractory tuyere to have a height equal to twicev that of any iron or metal tuyre, thereby greatly increasing the active burning surface of the furnace as well as, in corresponding degree, the capacity. of the furnace to burn fuel also, in comparison with an iron tuyere, greater efliciency for an equal quantity of coal to be burned per hour er retort; the static pressure in the air cham er beneath the 'tuyeres will be greatly reduced due to the larger burning surface of my refractory tuyeres as compared to that of iron tuyeres, zhereby reducing labor of the air supply Another point of advantage in my refractory tuyere s that the expansive and contractive action is many times less than that of iron or other metal and therefore the block will not crack and become useless. This advantage together with the great heat resisting quality of my refractory tuyere insures a lastin fuel burning surface, eliminating costly s ut downs for repairs, and effects a great saving of material and labor. However, my invention is not limited to the tuyre blocks for automatic stokers, but can be employed as horizontal fire blocks, or grates, as will be further explained.

Referring to the attached drawings illus trating preferred embodiments of the invention F 1 is a longitudinal section through the center line of a row of my refractory tuyeres as assembled in an automatic underfeed stoker;

Fig. 2 is an enlarged perspective view of one form of tuyere block of refractory material;

Fig. 3 is a perspective view of, the overfeed grate block;

Fig. 4 is an enlarged side View of a refractory grate block suitable for use in connection with retorts in automatic underfeed stokers;

Fig. 5 being a plan view and a cross sectional view through one row of tuyere openings;

Fig. 6 an enlarged longitudinal sectional view of the same; and

, Fig. 7 is afragmentary lan view of an underfeed stoker furnace s owing the refractory tuyere blocks as applied to the retorts and the refractory grate blocks as applied to the overfeed portion of the furnace.

It will be appreciated that my invention contemplates and includes the formation of any desired type or form in contour of tuyere block. Fire clay or similar refractory material lends itself with peculiar adaptability to such conformation. By having the surfaces of the refractory material on which the fuel rests and is moved, perforated with a considerable number of recesses, through which cool air under pressure is forced, these clay tuyere blocks are kept remarkably cool and are thus automatically preserved Furthermore the fuel supporting surfaces are fire resistant and the pressure of the air coming through the plurality of openingsjniaintains these openings free of fuel, reserves and prevents the surface of the c ay from being quickly burned out, prevents clinkers forming and acts equally with iron plates to stimulate combustion of the fuel in'the retort. ll have preferably illustrated the present invention as applied to the type of retort of the automatic stoker of'my said prior application wherein a gravity feed is utilized in addition to the'power pistons, the invention is not limited to this type of Stoker but ma am is lherein shown for illustrative purposes on y.

Referring to the drawing and as shown in Fig. 1, the usual type of retort is indicated at.1, a plurality of such retorts being arranged parallel and preferably at suitable angle, bein supported upon iron girders or the like esignated at 2 and the front wall, a fragment being shown at 3. A plurality of tuyere blocks designated at 5, 5, Fig.1, are supplied, these tuyere blocks having usual fuel supporting surfaces 6 arranged substantially in the same inclination throughout as shown in Figs. 1 and 2, through which a plurality of perforations 7, 7 7, 7, are formed. These tuyere blocks of refractory material, can be of substantially the same form and contour, as those now made of iron. Preferably, however, I make my refractory material of slightly greater thickness toaiford better wear resisting and longer life durin burning. These tuyere blocks 5 may be 0 any dimensions for units and may carry the sides 8, 8, to rest upon the supporting retort surfaces as shown at dotted line 9. A source of air under ressure, designated at 10, is supplied to orce the air outwardly through the openings 7 n a manner similar to that employed in iron construction.

I prefer to form these tuyere blocks of refractory material with a plurality of strengthening floors or webs 12, which also will hold inany siftings which come through the openings 7 and thus choking up the air space underneat The overfeed grate block 15 is clearly shown in Figs, 1 and 3, wherein a plurality of air openings 16, 16, 17, 17, are formed, pref erably of different diameters. The overfeed grate portions may be in suitable sections, preferably one for each retort'and therefore arranged side by side for as many retorts as desired, these being supported on iron brackets or frames 18 or in any other'suitable manner. Preferably 1 form this overfeed grate with a groove 24 adapted to fit over and interlock upon a memberv 19 carried by the bracket 18, but any other suitable means can be employed. I may also form the dump grate 20 with a fire brick lining, coating or surface, the same being supported on metallic cross brackets 21, held by a crossbar 22 and adapted to swing upon a pivot 23. i

In Figs l, 5 and 6 I have illustrated in an enlarged and detailed form tuyere blocks of substantially the same type, but a d ferent contour from the one shown in FM. 0

of f is 50111185 Of u tnntiei thicknes revent t These tuyeres 30 are formed with a for 4 I to insure long life and wear and 'with a rality of air openings 35 therethrough.

a inforcing floors 37, 38 and 39 are fitted,

.which may be of'iron to catch the siftings openings 35.

and prevent choking the air supply chamher orchannel beneath the tuyere, these plates being slidable'and removable through ooves .40, 40, formed in the-sides of t e ,ftuyere blocks. Siftings through-the openings can only take place at such time 'as the air sup 1y to the air chamber or'channelisshut o when the movement of the fuel bed over the tuyeres has a tendency to-workithe fuel into and through the o enin and onto the plates 39 which hold t e si ings until the-'airis again admitted, thus forcing the siftings bac into'the fuel bed through the.

In F'g. 7 is illustratedv a fragmentary plan view of an underfeed stoker furnace of the'type illustrated in Fig. 1 and show.-

ing the type of tuyere blocks. illustrated in Fig. 2,such tuyere blocks bein designated rior of block. Also by the numeral 6 and showing't erethrough the perforations 7 extending into the inteth-is view shows clearly the arrangement and location of'the floors 12 and also shows the retort sides!) onwhich sure, resists disintegration to a high degree ore,

' the tuyere blocks rest.

It will :be readily apipreciated thatmy idea .of a fire brick for will afford a convenient, economical, easily obtainable and quickly renewable construc tion. Fire brick, particular when supplied with a substantial volume 0 air under presand such refractory materialwill, there in many instances, outlast the iron grates,-

- and tuyere blocks, now generally employed.

I believe that my conception :of 'refractor material for this use and purpose, is new and important. I am well aware of the very-- general use ofifire brick for'furnace walls side walls, back wall and front wall, as wel 1 as roof, but I believe it to be a distinct novelty to, endeavor: to apply such or similar,re-'

'fractory material in a form and contour suitable for use as a fuel supportin grate and surface; It is this new use and eature,

together with the employment of such refractory material in connection with forced draft, which enables the same to be racticable, which I claim as new. Sue rere grate purposes,

pecially new and useful in connection with automatic stokers.

walls being of fire brick and the fuel supporting surface being of my new refractory blocks. Thus the metallic surfaces are "protected and repairing these surentirely faces is greatly simplified and cheapened, while the life of the furnace or stoker, without repairs, is greatly increased. No allowance for uneven expansion and contraction of the iron'and walls is needed, while the forced draft assing through the grates, maintains the-re actory material inits integrity.

Myinvention of a tuyere block having lfract ory material for tuyere blocks is This invention enables the fuel or fire area I ,of a furnace to be entirely'lined with're- 'fractory material, the front, side and bridge removable and renewable plates or floors is believedto be broadly new and applicable to tuyeres of, any kind of material, either refractory, or of metal.

My invention 'is further described and defined in the form of claims as follows:

7 1. A-tuyere block for automatic stokers,

comprisingan arched body portion having its s des spaced apart and extending parallel ing an arched body portion of refractory material having its sides spaced apart and extending parallel to each other, the outer arched portion actin as; a fuel supporting and fue burning sur ace, and a plurality of metallic floors arallelly arranged and extendingfrom-t e inner side of said arched body portion into said air channels, and

said floors renewable separately from said' arched body portion.

In testimony-whereof, I have signed my name to this specification.

OSCAR O. NYGAARD. 

